thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a rare haematological disease of unknown aetiology. This thrombotic microangiopathy is characterized by microvascular lesions with platelet aggregation.

Thrombotic thrombocytopenic purpura (TTP) is found in adults and can be associated with pregnancy, cancer, autoimmune diseases, bone marrow transplantation, drugs and bacterial as well as viral infections. Even if TTP is immediately treated in an adequate manner, it still shows a mortality of up to 20%.

Etiology - Associations

 pregnancy-associated thrombotic thrombocytopenic purpura
 cancer-associated thrombotic thrombocytopenic purpura

• occult adenocarcinoma

 autoimmune diseases
 bone marrow allograft (7806094, 2297591)

• allogeneic stem cell transplantation (11043426)
• with fatal disseminated adenoviral infection (11697511)

 drugs-associated thrombotic thrombocytopenic purpura

• cyclosporin-associated thrombotic thrombocytopenic purpura
• statin (15356359)

 bacterial infections

• leptospirosis (2262572)
• mycoplasma (10838456)

 viral infections

Synopsis

 renal lesions
 pulmonary lesions
 splenic lesions

• splenomegaly
• splenic arterial thrombi
• splenic arteriolar thrombi
• periodic acid-Schiff-positive diastase-resistant hyaline subendothelial deposits (SEDs)
• transition between thrombi and SEDs in splenic arterioles
• platelets or platelet-related material in SEDs and thrombi
• hyperplasia of white pulp (B-cells and germinal centers)
• splenic periarteriolar concentric fibrosis (onion-skin appearance)
   splenic hemosiderosis (siderophages and prominent iron deposits)
• splenic hemophagocytosis
• splenic extramedullary hematopoiesis
• splenic blood lakes
• splenic infarcts
• splenic endothelial hyperplasia
• no splenic microaneurysms

References

 Aster RH. Thrombotic thrombocytopenic purpura (TTP)—an enigmatic disease finally resolved? Trends Mol Med. 2002 Jan;8(1):1-3. PMID: 11796254

 Allford SL, Machin SJ. Current understanding of the pathophysiology of thrombotic thrombocytopenic purpura. J Clin Pathol. 2000 Jul;53(7):497-501. PMID: 10961171

 Saracco SM, Farhi DC. Splenic pathology in thrombotic thrombocytopenic purpura. Am J Surg Pathol. 1990 Mar;14(3):223-9. PMID: 2106272